抄録
The noble gas dilution effects on the plasma parameters have been studied both for Ar+O2 and He+O2 mixture gas positive column plasmas using the modified Schottky's theory. Theoretical results show that the dominant ion species in Ar+O2 plasmas is O2+ whereas it is O+ in He+O2 plasmas. In Ar+O2 plasmas, the density of O radicals is much smaller and the density of O- negative ions is much larger than those of He+O2 plasma. These differences can be explained by the difference between electron temperature in Ar+O2 and He+O2 mixture gas plasmas. Experiments have been carried out using the electrostatic probe, the quadrupole mass spectrometer and the optical spectroscopic methods to measure the electron temperature, the density of O radicals and O2+ ions. Experimental results agree well with the theoretical results.
